Analysis Commands

In OpenSees, an analysis is an object which is composed by the aggregation of component objects. It is the component objects which define the type of analysis that is peformed on the model. The component classes, as shown in the figure below, consist of the following:

1. ConstraintHandler -- determines how the constraint equations are enforced in the analysis -- how it handles the boundary conditions/imposed displacements
2. DOF_Numberer -- determines the mapping between equation numbers and degrees-of-freedom
3. Integrator -- determines the predictive step for time t+dt
4. SolutionAlgorithm -- determines the sequence of steps taken to solve the non-linear equation at the current time step
5. SystemOfEqn/Solver -- within the solution algorithm, it specifies how to store and solve the system of equations in the analysis
6. Convergence Test -- determines when convergence has been achieved.

<uml> package "OpenSees Analysis" #DDDDDD

abstract class Integrator abstract class Analysis abstract class SystemOfEqn abstract Class ConvergenceTest abstract class Algorithm Analysis o- ConstraintHandler Analysis o- Numberer Analysis o- Algorithm Analysis o- ConvergenceTest Analysis o- Integrator Analysis o- SystemOfEqn </uml>

The following are the modeling commands that have been added to interpreter to create the finite element model:

File:Example5.1.tcl

The following Analysis commands are added to the interpreter to create the Analysis and perform the analysis:

1. constraints Command
2. numberer Command
3. system Command
4. test Command
5. algorithm Command
6. integrator Command
7. analysis Command
8. eigen Command
9. analyze Command